Report: US exploring possibility of controversial ‘challenge trial’ for COVID-19 vaccine

Federal health officials have begun preliminary work to establish protocols of a “challenge” trial of a COVID-19 vaccine, including manufacturing a strain of the virus that could be used, Reuters reported on Friday.

A “challenge trial” is a controversial idea to deliberately infect a few hundred young, healthy volunteers with the novel coronavirus in a controlled environment to test a possible vaccine. 

Multiple clinical studies of different vaccines are already underway, and a challenge trial is not likely to replace them, the National Institute of Allergy and Infectious Diseases (NIAID) told Reuters.

But The Hill has previously reported that the idea has been gaining some ground among certain advocacy groups and lawmakers. 

NIAID has started reportedly started its initial planning. The agency is prioritizing large-scale field trials to evaluate COVID-19 vaccine candidates, but is open to the possibility of using challenge trials for future generations of vaccines or treatments.

The Hill has reached out to NIAID for comment.

A challenge trial would deliberately infect a few hundred young, healthy volunteers who have first been given either the potential vaccine or a placebo. Those picked would be well informed about the risks. 

That would allow the effectiveness of a vaccine to be determined faster than a traditional clinical trial, which would require that researchers wait for some of the participants to become infected in the course of their daily lives.  

Challenge trials have been conducted in the past, but they are usually done to test vaccines for diseases that can be cured, like malaria. It would be a sharp break from precedent to do a challenge trial for a virus with no known cure that is as deadly as the coronavirus. Even if the volunteers were all young and healthy, that would not entirely reduce the risk of serious illness. 

In addition, they are also conducted among much smaller groups, raising questions about how such trials would be helpful at this stage of the pandemic, when the virus is so widespread.

Some of the top vaccine candidates are already operating under an accelerated time frame, and have begun stage three trials testing safety and efficacy in tens of thousands of people.